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This is the ESOcast!
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Cutting-edge science and life behind the scenes of ESO,
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the European Southern Observatory,
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exploring the ultimate frontier with our host Dr J, a.k.a. Dr Joe Liske.
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Hello and welcome to this special episode of the ESOcast.
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Leading up to ESO’s 50th anniversary in October 2012,
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we will showcase eight special features
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portraying ESO’s first 50 years of exploring the southern sky.
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Finding Life
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Have you ever wondered about life in the Universe?
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Inhabited planets orbiting distant stars?
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Astronomers have — for centuries.
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After all, with so many galaxies, and each with so many stars,
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how could the Earth be unique?
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In 1995, Swiss astronomers Michel Mayor and Didier Queloz
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were the first to discover an exoplanet orbiting a normal star.
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Since then, planet hunters have found many hundreds of alien worlds.
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Large and small, hot and cold, and in a wide variety of orbits.
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Now, we’re on the brink of discovering Earth’s twin sisters.
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And in the future: a planet with life — the Holy Grail of astrobiologists.
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The European Southern Observatory plays an important role
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in the search for exoplanets.
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Michel Mayor’s team found hundreds of them from Cerro La Silla,
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ESO’s first Chilean foothold.
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Here’s the CORALIE spectrograph,
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mounted on the Swiss Leonhard Euler Telescope.
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It measures the tiny wobbles of stars, caused by the gravity of orbiting planets.
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ESO’s venerable 3.6-metre telescope is also hunting for exoplanets.
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The HARPS spectrograph is the most accurate in the world.
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So far, it has discovered more than 150 planets.
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Its biggest trophy:
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a rich system containing at least five and maybe as many as seven alien worlds.
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But there are other ways to find exoplanets.
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In 2006, the 1.5-metre Danish telescope helped to discover a distant planet
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that is just five times more massive than the Earth.
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The trick? Gravitational microlensing.
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The planet and its parent star passed in front of a brighter star in the background,
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magnifying its image.
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And in some cases, you can even capture exoplanets on camera.
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In 2004, NACO, the adaptive optics camera on the Very Large Telescope,
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took the first image ever of an exoplanet.
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The red dot in this image is a giant planet orbiting a brown dwarf star.
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In 2010, NACO went one step further.
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This star is 130 light-years away from Earth.
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It is younger and brighter than the Sun, and four planets circle around it in wide orbits.
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NACO’s eagle-eyed vision made it possible to measure the light of planet c
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— a gas giant ten times more massive than Jupiter.
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Despite the glare of the parent star,
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the feeble light of the planet could be stretched out into a spectrum,
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revealing details about the atmosphere.
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Today, many exoplanets are discovered when they transit across their parent stars.
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If we happen to see the planet’s orbit edge-on,
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it will pass in front of its star every cycle.
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Thus, tiny, regular brightness dips in the light of a star
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betray the existence of an orbiting planet.
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The TRAPPIST telescope at La Silla will help search for these elusive transits.
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Meanwhile,
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the Very Large Telescope has studied a transiting planet in exquisite detail.
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Meet GJ1214b, a super-Earth 2.6 times larger than our home planet.
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During transits, the planet’s atmosphere partly absorbs the light of the parent star.
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ESO’s sensitive FORS spectrograph revealed that GJ1214b
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might well be a hot and steamy sauna world.
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Gas giants and sauna worlds are inhospitable to life.
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But the hunt is not over yet.
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Soon, the new SPHERE instrument will be installed at the VLT.
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SPHERE will be able to spot faint planets in the glare of their host stars.
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In 2016, the ESPRESSO spectrograph will arrive at the VLT
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and greatly surpass the current HARPS instrument.
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And ESO’s Extremely Large Telescope, once completed,
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may well find evidence for alien biospheres.
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On Earth, life is abundant.
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Northern Chile offers its share of condors, vicuñas, vizcachas and giant cacti.
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Even the arid soil of the Atacama desert teems with hardy microbes.
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We’ve found the building blocks of life in interstellar space.
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We’ve learnt that planets are abundant.
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Billions of years ago, comets brought water and organic molecules to Earth.
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Wouldn’t we expect the same thing to happen elsewhere?
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Or are we alone?
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It’s the biggest question ever.
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And the answer is almost within reach.
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This is Dr J, signing off from this special episode of the ESOcast.
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Join me again next time for another cosmic adventure.
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ESOcast is produced by ESO,
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the European Southern Observatory.
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ESO, the European Southern Observatory,
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is the pre-eminent intergovernmental science and technology organisation in astronomy.
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Among both ground- and space-based observatories, ESO is the most productive observatory in the world.
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Transcription by ESO; translation by —